fix(agentcompat): retain transfer sentinel handles

Co-authored-by: naiba/CloudCode <hi+cloudcode@nai.ba>

integration/agentcompat/internal/scenario/transfer.go

@@ -97,6 +97,7 @@ func (Transfer) RunWithEvidence(ctx context.Context, input TransferInput) (resul
 		result, runErr = transferFinish(assertions, err)
 		return result, transferEvidence, runErr
 	}
+	defer sentinels.close()
 	execution := transferExecution{
 		client:       dashboardInstance.Clients().MCP,
 		serverID:     serverID,

integration/agentcompat/internal/scenario/transfer_sentinels.go

@@ -15,23 +15,31 @@ import (
 var transferSentinelContent = []byte("outside-transfer-root-sentinel")
 
 type transferSentinels struct {
-	paths []string
+	root  *os.Root
+	names []string
 }
 
-func newTransferSentinels(root fixture.AgentRoot, workspaceRoot string) (transferSentinels, error) {
-	directPath := filepath.Join(workspaceRoot, "outside-transfer-sentinel")
-	symlinkDirectory := filepath.Join(workspaceRoot, "outside-transfer-directory")
-	symlinkTarget := filepath.Join(symlinkDirectory, "target-sentinel")
-	if err := os.Mkdir(symlinkDirectory, 0o700); err != nil {
+func newTransferSentinels(root fixture.AgentRoot, workspaceRoot string) (result transferSentinels, err error) {
+	workspace, err := os.OpenRoot(workspaceRoot)
+	if err != nil {
+		return transferSentinels{}, fmt.Errorf("open transfer sentinel root: %w", err)
+	}
+	defer func() {
+		if err != nil {
+			err = errors.Join(err, workspace.Close())
+		}
+	}()
+	result = transferSentinels{root: workspace, names: []string{"outside-transfer-sentinel", "outside-transfer-directory/target-sentinel"}}
+	if err := workspace.Mkdir("outside-transfer-directory", 0o700); err != nil {
 		return transferSentinels{}, fmt.Errorf("create transfer sentinel directory: %w", err)
 	}
-	for _, path := range []string{directPath, symlinkTarget} {
-		if err := os.WriteFile(path, transferSentinelContent, 0o600); err != nil {
+	for _, name := range result.names {
+		if err := workspace.WriteFile(name, transferSentinelContent, 0o600); err != nil {
 			return transferSentinels{}, fmt.Errorf("write transfer sentinel: %w", err)
 		}
 	}
 	symlinkPath := filepath.Join(root.Absolute(), "linked")
-	if err := os.Symlink(symlinkDirectory, symlinkPath); err != nil {
+	if err := os.Symlink(filepath.Join(workspaceRoot, "outside-transfer-directory"), symlinkPath); err != nil {
 		return transferSentinels{}, fmt.Errorf("create transfer sentinel symlink: %w", err)
 	}
 	if _, err := root.Path("../outside-transfer-sentinel"); err == nil {
@@ -40,12 +48,12 @@ func newTransferSentinels(root fixture.AgentRoot, workspaceRoot string) (transfe
 	if _, err := root.Path("linked/target-sentinel"); err == nil {
 		return transferSentinels{}, errors.New("transfer AgentPath accepted symlink parent")
 	}
-	return transferSentinels{paths: []string{directPath, symlinkTarget}}, nil
+	return result, nil
 }
 
 func (sentinels transferSentinels) unchanged() (bool, error) {
-	for _, path := range sentinels.paths {
-		content, err := os.ReadFile(path)
+	for _, name := range sentinels.names {
+		content, err := sentinels.root.ReadFile(name)
 		if err != nil {
 			return false, fmt.Errorf("read transfer sentinel: %w", err)
 		}
@@ -55,3 +63,5 @@ func (sentinels transferSentinels) unchanged() (bool, error) {
 	}
 	return true, nil
 }
+
+func (sentinels transferSentinels) close() error { return sentinels.root.Close() }